Performance evaluation of Nash bargaining solution based user association in HetNet

In heterogeneous network (HetNet), the combined cell range extension (CRE) and enhanced inter-cell interference coordination (elCIC) proposed by 3GPP is considered as the most effective user association scheme. However, this scheme requires strict frame synchronization between macrocells and small cells. In this paper, we propose a Nash bargaining solution (NBS) based user association scheme which does not require such synchronization between cells in different tiers. The proposed scheme formulates user association optimization problem as a Nash bargaining problem. The objective is to maximize the sum data rate related utility of all users in the overall system while guaranteeing user´s minimal data rate and considering the user fairness. The simulation results show the proposed scheme can achieve higher sum rate of all users and better user fairness compared with the combined CRE and elCIC based user association scheme. Moreover, the proposed scheme has low computational complexity by applying Hungarian algorithm.